I have been following the AIS stuff pretty heavily and will be plunging for the purchase of a AIS B transponder now that they are FCC approved. I actually find that for normal cruising in the Puget Sound that AIS works incredibly well in lieu of having a Radar up and running. Combine Radar and AIS you got a kick butt target tracking system.
However ran across this link from the guys over at Navagear.com: Live Ships Map - AIS - Vessel Traffic System
It doesn't cover everywhere - and I found the data for Puget Sound only focused around the straits but for some of you geeks out there - link may be of interest.